U.S. patent application number 14/089308 was filed with the patent office on 2014-03-27 for apparatus and method for charging battery.
This patent application is currently assigned to LG CHEM, LTD.. The applicant listed for this patent is LG CHEM, LTD.. Invention is credited to Cheol-Taek KIM, Kyu-Ha PARK.
Application Number | 20140084851 14/089308 |
Document ID | / |
Family ID | 48437951 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140084851 |
Kind Code |
A1 |
PARK; Kyu-Ha ; et
al. |
March 27, 2014 |
APPARATUS AND METHOD FOR CHARGING BATTERY
Abstract
Disclosed is an apparatus (and method) for charging a battery
having a voltage measuring unit for measuring a voltage, a control
unit for outputting a charge control signal corresponding to an
early charging mode in which the battery is charged until a voltage
of the battery rises to a preset cut-off voltage (Vc) and a charge
control signal corresponding to a late charging mode in which the
battery is charged while lowering a charge power in phases, and a
charging unit for providing a charge power corresponding to the
charge control signal to the battery, wherein a point of lowering
the charge power in phases is associated with a point at which the
voltage of the battery reaches the cut-off voltage again by the
lowered charge power. Therefore, a voltage level reached at full
charge of a battery may be raised in a simple and efficient
way.
Inventors: |
PARK; Kyu-Ha; (Seoul,
KR) ; KIM; Cheol-Taek; (Daejeon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
|
KR |
|
|
Assignee: |
LG CHEM, LTD.
Seoul
KR
|
Family ID: |
48437951 |
Appl. No.: |
14/089308 |
Filed: |
November 25, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/KR2012/008043 |
Oct 4, 2012 |
|
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14089308 |
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Current U.S.
Class: |
320/107 ;
320/160 |
Current CPC
Class: |
H02J 7/007 20130101;
B60L 53/53 20190201; Y02T 90/16 20130101; Y02T 90/12 20130101; B60L
53/62 20190201; B60L 58/15 20190201; Y02T 10/7072 20130101; B60L
2240/547 20130101; Y02B 40/00 20130101; Y02T 90/14 20130101; H02J
7/04 20130101; Y02T 10/70 20130101; H02J 7/045 20130101 |
Class at
Publication: |
320/107 ;
320/160 |
International
Class: |
H02J 7/00 20060101
H02J007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2011 |
KR |
10-2011-0100664 |
Oct 4, 2012 |
KR |
10-2012-0110116 |
Claims
1. An apparatus for charging a battery, comprising: a voltage
measuring unit for measuring a voltage of a battery; a control unit
for outputting a charge control signal corresponding to an early
charging mode in which the battery is charged until a voltage of
the battery rises to a preset cut-off voltage (Vc) and a charge
control signal corresponding to a late charging mode in which the
battery is charged while lowering a charge power in phases; and a
charging unit for providing a charge power corresponding to the
charge control signal to the battery, wherein a point of lowering
the charge power in phases is associated with a point at which the
voltage of the battery reaches the cut-off voltage again by the
lowered charge power.
2. The apparatus for charging a battery according to claim 1,
wherein the cut-off voltage (Vc) is set higher than an open circuit
voltage when the battery is fully charged.
3. The apparatus for charging a battery according to claim 1,
wherein the cut-off voltage (Vc) is set so that an open circuit
voltage when the battery finishes charging is 95% or above an open
circuit voltage when the battery is fully charged.
4. The apparatus for charging a battery according to claim 1,
wherein in the late charging mode, a phased decrement (.DELTA.P) of
the charge power is 1/5 or below a charge power (CP0) applied when
the early charging mode terminates.
5. The apparatus for charging a battery according to claim 1,
wherein in the late charging mode, a phased decrement (.DELTA.P) of
the charge power is constant.
6. The apparatus for charging a battery according to claim 1,
wherein in the late charging mode, a phased decrement (.DELTA.P) of
the charge power proportionally increases or decreases.
7. The apparatus for charging a battery according to claim 1,
wherein the late charging mode terminates when a charge power level
at the present point, which has been lowered in phases, reaches a
preset critical value.
8. The apparatus for charging a battery according to claim 7,
wherein the critical value is 0 W.
9. The apparatus for charging a battery according to claim 1,
wherein in the late charging mode, a phased decrement (.DELTA.P) of
the charge power is constant, and wherein the late charging mode
terminates when a charge power level at the present point, which
has been lowered in phases, reaches a preset critical value.
10. The apparatus for charging a battery according to claim 9,
wherein the critical value is 0 W.
11. The apparatus for charging a battery according to claim 1,
wherein in the early charging mode, the battery is charged by means
of a constant-power manner, a constant-current manner, a
constant-voltage manner, or their mixtures.
12. The apparatus for charging a battery according to claim 1,
wherein the control unit outputs a charge control signal for
lowering a charge voltage, a charge current, or both the charge
voltage and the charge current, in the late charging mode.
13. The apparatus for charging a battery according to claim 12,
wherein when outputting a charge control signal for lowering both a
charge voltage and a charge current in the late charging mode, the
control unit outputs a charge control signal so that the charge
voltage approaches the cut-off voltage.
14. The apparatus for charging a battery according to claim 12,
wherein when outputting a charge control signal for lowering a
charge current in the late charging mode, the control unit outputs
a charge control signal so that the charge voltage rises according
to a preset voltage range.
15. The apparatus for charging a battery according to claim 1,
further comprising a memory unit that stores the cut-off voltage,
the phased decrement of the charge power, and a charge power
condition when the late charging mode terminates.
16. A battery driving system, comprising: a battery; a load for
receiving power from the battery; and an apparatus for charging a
battery, defined in the claims 1.
17. The battery driving system according to claim 16, wherein the
load is an electric-driven unit or a portable device.
18. A battery pack, comprising: a battery; and an apparatus for
charging a battery, defined in the claim 1.
19. A method for charging a battery, comprising: an early charging
stage in which a battery is charged until a voltage of the battery
rises to a preset cut-off voltage (Vc); and a late charging stage
in which the battery is charged while lowering a charge power in
phases, wherein a point of lowering the charge power in phases is
associated with a point at which the voltage of the battery reaches
the cut-off voltage again by the lowered charge power.
20. The method for charging a battery according to claim 19,
wherein the cut-off voltage (Vc) is set higher than an open circuit
voltage when the battery is fully charged.
21. The method for charging a battery according to claim 19,
wherein the cut-off voltage (Vc) is set so that an open circuit
voltage when the battery finishes charging is 95% or above an open
circuit voltage when the battery is fully charged.
22. The method for charging a battery according to claim 19,
wherein in the late charging stage, a phased decrement (.DELTA.P)
of the charge power is 1/5 or below a charge power (CP0) applied
when the early charging stage terminates.
23. The method for charging a battery according to claim 19,
wherein in the late charging stage, a phased decrement (.DELTA.P)
of the charge power is constant.
24. The method for charging a battery according to claim 19,
wherein in the late charging stage, a phased decrement (.DELTA.P)
of the charge power proportionally increases or decreases.
25. The method for charging a battery according to claim 19,
wherein the late charging stage terminates when a charge power
level at the present point, which has been lowered in phases,
reaches a preset critical value.
26. The method for charging a battery according to claim 25,
wherein the critical value is 0 W.
27. The method for charging a battery according to claim 19,
wherein in the late charging stage, a phased decrement (.DELTA.P)
of the charge power is constant, and wherein the late charging
stage terminates when a charge power level at the present point,
which has been lowered in phases, reaches a preset critical
value.
28. The method for charging a battery according to claim 27,
wherein the critical value is 0 W.
29. The method for charging a battery according to claim 19,
wherein in the early charging stage, the battery is charged by
means of a constant-power manner, a constant-current manner, a
constant-voltage manner, or their mixtures.
30. The method for charging a battery according to claim 19,
wherein the late charging stage lowers a charge power in phases by
lowering a charge voltage, a charge current, or both the charge
voltage and the charge current.
31. The method for charging a battery according to claim 30,
wherein when outputting a charge control signal for lowering both a
charge voltage and a charge current, the late charging stage lowers
a charge power in phases so that the charge voltage approaches the
cut-off voltage.
32. The method for charging a battery according to claim 30,
wherein when outputting a charge control signal for lowering a
charge current, the late charging stage lowers a charge power in
phases so that the charge voltage rises according to a preset
voltage range.
33. The method for charging a battery according to claim 19,
further comprising: storing the cut-off voltage, the phased
decrement of the charge power, and a charge power condition when
the late charging stage terminates.
Description
CROSS-REFERENCE TO RELATED .DELTA.PPLICATION
[0001] The present application is a continuation of International
Application No. PCT/KR2012/008043 filed on Oct. 4, 2012, which
claims priority to Korean Patent Application No. 10-2011-0100664
filed on Oct. 4, 2011 and Korean Patent Application No.
10-2012-0110116 filed on Oct. 4, 2012 in the Republic of Korea, the
disclosures of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to an apparatus and method
for charging a battery, and more particularly to an apparatus and
method capable of effectively raising a voltage level reached at
full charge of a battery by improving a charging algorithm.
BACKGROUND ART
[0003] Recently, the demand for portable electronic products such
as notebooks, video cameras, cellular phones or the like is rapidly
increasing, and electric vehicles (EV), hybrid electric vehicles
(HEV), energy storage batteries, robots, satellites or the like are
developed in earnest. Accordingly, a high-performance secondary
battery allowing repeated charging/discharging is actively
studied.
[0004] Secondary batteries commercially used at the present include
nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc
batteries, lithium secondary batteries or the like, among which the
lithium secondary batteries are in the limelight due to their very
low self-discharge ratio, high energy density and free
charging/discharging since a memory effect does not substantially
occur in comparison to nickel-based secondary batteries.
[0005] Such a secondary battery is charged to operate within an
operation voltage. An operation voltage of a general lithium
secondary battery is in a range of 3.7V to 4.2V. Therefore, when
the secondary battery is fully charged, the secondary battery has
an open circuit voltage of 4.2V. However, a secondary battery is
not always charged under the same condition. In other words, a
secondary battery may be charged while being connected to a load or
supplying power to a load. For example, a battery loaded on a
hybrid electric vehicle may receive a charge power from an engine
together with supplying power to a vehicle-driving motor. Like
this, if a voltage of a secondary battery is measured while the
secondary battery is being connected to a load or
charged/discharged, it is impossible to measure an accurate voltage
of the secondary battery due to the load effect. As a result, when
charging a secondary battery connected to a load, it is difficult
to check whether the secondary battery reaches full charge by only
measuring a voltage of the secondary battery.
[0006] In order to solve this problem, an algorithm for charging a
battery based on a state of charge (SOC) has been proposed. When a
secondary battery supplies power to a load, a current supplied from
the secondary battery to the load is measured, and then the
measured currents are added and stored as a total discharge
quantity. After that, during a charging process, the secondary
battery is not charged based on the voltage of the secondary
battery, but fully charged by a charge current supplied as much as
the total discharge quantity. However, this technique has problems
in that as the number of charging/discharging processes increases,
due to the accumulation of SOC measurement errors caused during the
charging/discharging processes, it becomes more difficult to reach
full charge. Therefore, there is needed a new charging algorithm
capable of achieving full charge.
DISCLOSURE
Technical Problem
[0007] The present disclosure is designed to solve the problems of
the related art, and therefore the present disclosure is directed
to providing an apparatus and method capable of efficiently
charging a battery in a simple way.
Technical Solution
[0008] In one aspect of the present disclosure, there is provided
an apparatus for charging a battery, which includes a voltage
measuring unit for measuring a voltage of a battery; a control unit
for outputting a charge control signal corresponding to an early
charging mode in which the battery is charged until a voltage of
the battery rises to a preset cut-off voltage Vc and a charge
control signal corresponding to a late charging mode in which the
battery is charged while lowering a charge power in phases; and a
charging unit for providing a charge power corresponding to the
charge control signal to the battery, wherein a point of lowering
the charge power in phases is associated with a point at which the
voltage of the battery reaches the cut-off voltage again by the
lowered charge power.
[0009] According to the present disclosure, the cut-off voltage Vc
may be set higher than an open circuit voltage when the battery is
fully charged. Preferably, the cut-off voltage Vc may be set so
that an open circuit voltage when the battery finishes charging is
95% or above an open circuit voltage when the battery is fully
charged.
[0010] According to the present disclosure, the early charging mode
may charge the battery by means of a constant-power manner, a
constant-current manner, a constant-voltage manner, or their
mixtures.
[0011] Meanwhile, in the late charging mode, a phased decrement
.DELTA.P of the charge power may be set to be 1/5 or below a charge
power CP0 applied when the early charging mode terminates.
[0012] In addition, in the late charging mode, a phased decrement
.DELTA.P of the charge power may be set to be constant or may be
set to proportionally increase or decrease.
[0013] According to the present disclosure, the late charging mode
may terminate when a charge power level at the present point, which
has been lowered in phases, reaches a preset critical value. For
example, the critical value may be set to be 0 W.
[0014] The apparatus for charging a battery according to the
present disclosure may further include a memory unit that stores
the cut-off voltage, the phased decrement of the charge power, and
a charge power condition when the late charging mode
terminates.
[0015] The apparatus for charging a battery according to the
present disclosure may be one component of a battery driving system
which includes a battery and a load for receiving power from the
battery.
[0016] The battery driving system may be an electric vehicle (EV),
a hybrid electric vehicle (HEV), an electric bike (E-Bike), a power
tool, an energy storage system, an uninterruptable power supply
(UPS), a portable computer, a cellular phone, a portable audio
device, a portable video device or the like, and the load may be a
motor for giving a rotating force by the power supplied by the
battery or a power conversion circuit for converting the power
supplied by the battery into power required by various circuit
parts.
[0017] The apparatus for charging a battery according to the
present disclosure may be one component of a battery pack which
includes a cell assembly in which a plurality of battery cells is
connected in series or in parallel and a battery management system
(BMS) for controlling charging/discharging of the cell
assembly.
[0018] In this case, the battery charging apparatus may be
integrated with the BMS or configure a separate circuit device.
[0019] In another aspect of the present disclosure, there is also
provided a method for charging a battery, which includes an early
charging stage in which a battery is charged until a voltage of the
battery rises to a preset cut-off voltage Vc; and a late charging
stage in which the battery is charged while lowering a charge power
in phases, wherein a point of lowering the charge power in phases
is associated with a point at which the voltage of the battery
reaches the cut-off voltage again by the lowered charge power.
Advantageous Effects
[0020] According to an aspect of the present disclosure, it is
possible to raise a voltage level reached at full charge of a
battery in a simple and efficient way.
[0021] According to another aspect of the present disclosure, a
voltage level reached at full charge of a battery may be raised by
setting a cut-off voltage Vc and a phased charge power decrement
.DELTA.P in consideration of characteristics of a battery to be
charged, service environments or the like.
[0022] According to another aspect of the present disclosure, since
a charging process is not performed based on a measurement error
which may occur during repeated charging processes, a voltage level
reached at full charge of a battery may be raised regardless of the
number of charging processes.
DESCRIPTION OF DRAWINGS
[0023] The accompanying drawings illustrate preferred embodiments
of the present disclosure and, together with the foregoing
disclosure, serve to provide further understanding of the technical
spirit of the present disclosure. However, the present disclosure
is not to be construed as being limited to the drawings in
which:
[0024] FIG. 1 is a block diagram schematically showing a functional
configuration of an apparatus for charging a battery according to
an embodiment of the present disclosure;
[0025] FIG. 2 is a graph showing a voltage profile of a battery in
an early charging mode and a late charging mode according to an
embodiment of the present disclosure;
[0026] FIG. 3 is a graph showing a variation profile of a charge
power in the early charging mode and the late charging mode
according to an embodiment of the present disclosure; and
[0027] FIG. 4 is a schematic flowchart for illustrating a method
for charging a battery according to an embodiment of the present
disclosure.
BEST MODE
[0028] Hereinafter, preferred embodiments of the present disclosure
will be described in detail with reference to the accompanying
drawings. Prior to the description, it should be understood that
the terms used in the specification and the appended claims should
not be construed as limited to general and dictionary meanings, but
interpreted based on the meanings and concepts corresponding to
technical aspects of the present disclosure on the basis of the
principle that the inventor is allowed to define terms
appropriately for the best explanation. Therefore, the description
proposed herein is just a preferable example for the purpose of
illustrations only, not intended to limit the scope of the
disclosure, so it should be understood that other equivalents and
modifications could be made thereto without departing from the
spirit and scope of the disclosure.
[0029] First, a battery charging apparatus 100 according to an
embodiment of the present disclosure will be described.
[0030] FIG. 1 is a block diagram schematically showing a functional
configuration of a battery charging apparatus 100 according to an
embodiment of the present disclosure.
[0031] Referring to FIG. 1, the battery charging apparatus 100
according to an embodiment of the present disclosure includes a
voltage measuring unit 110, a control unit 120 and a charging unit
130.
[0032] The voltage measuring unit 110 measures a voltage of a
battery while the battery is being charged. The technique for
measuring a voltage of a battery is well known in the art and thus
not described in detail here.
[0033] The control unit 120 controls the charging unit 130 by means
of an early charging mode and a late charging mode. The early
charging mode is a charging mode in which a battery is initially
charged with a preset early charge power until a voltage of the
battery measured by the voltage measuring unit 110 rises to a
preset cut-off voltage Vc. The late charging mode is a charging
mode in which the battery is charged while lowering a late charge
power in phases based on the charge power when the early charging
mode terminates. The control unit 120 outputs charge control
signals corresponding to both charging modes to the charging unit
130.
[0034] The charging unit 130 provides a charge power, which
corresponds to the charge control signal output by the control unit
120, to the battery. For this, the charging unit 130 is
electrically coupled to a power supply unit (not shown) which
supplies power required for generation of a charge power. The power
supply unit may be, for example, a common electrical grid, a bulk
power storage device, a generator or the like, but the present
disclosure is not limited thereto. The charging technique for
giving a charge power of a certain magnitude to a battery is
already well known in the art and thus not described in detail
here.
[0035] Hereinafter, the early charging mode and the late charging
mode will be described in more detail with reference to FIGS. 2 and
3.
[0036] FIGS. 2 and 3 are graphs showing a voltage profile of a
battery and a variation profile of a charge power according to an
early charging mode and a late charging mode, respectively.
[0037] First, in the early charging mode, the control unit 120
controls the charging unit 130 so that the battery is charged with
a preset early charge power CP0. The early charge power CP0 may be
set in various ways according to characteristics of a battery to be
charged and user requirements. Therefore, the early charging mode
may be performed by means of a constant-power manner, a
constant-current manner, a constant-voltage manner, or their
mixtures.
[0038] Even though FIGS. 2 and 3 show a case in which the battery
is charged with the early charge power CP0 in a constant-power
manner, it is obvious that the early charge power CP0 may have a
fixed magnitude or a varying magnitude during a charging process
depending on the charging manner. In addition, in the early
charging mode, the control unit 120 controls so that the battery is
charged until a voltage of the battery measured by the voltage
measuring unit 110 rises to a preset cut-off voltage Vc.
[0039] According to the present disclosure, the cut-off voltage Vc
is set higher than an open circuit voltage when the battery is
fully charged. This considers that a voltage of a battery during a
charging process is higher than an open circuit voltage. If the
cut-off voltage Vc is set higher than the open circuit voltage when
the battery is fully charged as described above, a voltage reached
at full charge may be raised more efficiently.
[0040] Preferably, the cut-off voltage Vc may be set so that an
open circuit voltage of the battery when the battery finishes
charging is 95% or above an open circuit voltage when the battery
is fully charged. According to the present disclosure, an open
circuit voltage when the battery finishes charging varies according
to a set value of the cut-off voltage Vc. Therefore, various
cut-off voltages Vc may be set for a battery to be actually used,
and actual charging experiments may be performed according to
various cut-off voltages Vc to obtain various open circuit voltages
when the battery finishes charging. At this time, among the various
open circuit voltages when the battery finishes charging, obtained
through experiments, an open circuit voltage when the battery
finishes charging corresponding to 95% or above the open circuit
voltage when the battery is fully charged may be found. Therefore,
a cut-off voltage Vc corresponding to the open circuit voltage when
the battery finishes charging, which is 95% or above the open
circuit voltage when the battery is fully charged, may be set as a
cut-off voltage Vc of the present disclosure.
[0041] As described above, the cut-off voltage Vc may be set
variously according to characteristics of a battery to be charged
and user requirements. If the cut-off voltage Vc is set variously
according to characteristics of the battery, a voltage reached at
full charge may be raised more efficiently.
[0042] Next, in the late charging mode, the control unit 120
controls the charging unit 130 so that the battery is charged while
lowering a charge power in phases based on the charge power at the
point when the early charging mode terminates. At this time, the
point of lowering a charge power in phases is associated with a
point at which a voltage of the battery measured by the voltage
measuring unit 110 reaches the cut-off voltage Vc by the lowered
charge point.
[0043] In more detail, if a voltage of the battery charged with the
early charge power CP0 reaches the cut-off voltage Vc, the control
unit 120 controls the charging unit 130 so that the battery is
charged with a late charge power CP1, which is obtained by lowering
as much as a preset decrement .DELTA.P from the charge power CP0 at
the point when the early charging mode terminates. If the charging
unit 130 charges the battery with the late charge power CP1 so that
the voltage of the battery reaches the cut-off voltage Vc again,
the control unit 120 controls the charging unit 130 again so that
the battery is charged with a late charge power CP2 which is
obtained by lowering as much as a preset decrement .DELTA.P from
the late charge power CP1. The process of lowering a charge power
in phases in association with the cut-off voltage Vc repeats until
a level of the charge power decreases to a preset critical
value.
[0044] When outputting a charge control signal to the charging unit
130 in order to lower the late charge power in phases, the control
unit 120 may output to the charging unit 130 a charge control
signal for lowering a charge voltage, lowering a charge current, or
lowering both the charge voltage and the charge current.
[0045] For example, whenever the voltage of the battery reaches the
cut-off voltage Vc, the charge voltage output from the charging
unit 130 may be gradually lowered to approach the cut-off voltage
Vc, and simultaneously a charge current output from the charging
unit 130 may also be gradually lowered. At this time, the control
unit 120 outputs the charge control signal so that a multiplication
of the lowered charge voltage and the lowered charge current
corresponds to the preset charge power decrement .DELTA.P.
[0046] As another example, whenever the voltage of the battery
reaches the cut-off voltage Vc, the charge voltage output from the
charging unit 130 may be raised, and simultaneously the charge
current output from the charging unit 130 may be gradually lowered.
At this time, the increment of the charge voltage may be suitably
set for good charging in consideration of the cut-off voltage Vc of
the battery or an estimated present charge quantity of the battery.
In other words, as the late charging continues to perform, the
charge quantity of the battery will increase. At this time, even if
charging is not stopped and the open circuit voltage of the battery
is not directly measured, the estimated open circuit voltage of the
battery will still rise gradually. Therefore, the control unit 120
may output a charge control signal so that a voltage difference
between the charging unit 130 and the battery may be maintained.
Here, the control unit 120 outputs the charge control signal so
that a multiplication of the raised charge voltage and the lowered
charge current corresponds to the preset charge power decrement
.DELTA.P. At this time, the increment of the charge voltage may be
preset and stored in the memory unit 140. If the charge power is
controlled as above, the open circuit voltage of when the battery
is fully charged may be increased to the maximum available voltage
range of the battery.
[0047] FIGS. 2 and 3 show an example in which a charge power is
lowered six times by the same level based on the charge power CP0
when the early charging mode terminates, thereby terminating the
late charging mode when the charge power becomes 0 W. However, the
phased decrement .DELTA.P of the charge power and the critical
value of the charge power at which the late charging mode
terminates may be set variously according to characteristics of the
battery.
[0048] Meanwhile, in the embodiment depicted in FIG. 2, if the
voltage of the battery reaches the cut-off voltage Vc, the charging
process is interrupted for a moment, and then the battery is
charged again after the voltage of the battery is stabilized.
Generally, a voltage of a battery measured during a charging
process is higher than an open circuit voltage (OCV) of the
battery, and if the charging process is interrupted, the battery
voltage is slightly lowered while the voltage of the battery is
stabilized. FIG. 2 is to facilitate understanding of the voltage of
the battery reaching the preset cut-off voltage Vc again, and in
this embodiment, a short suspension period is given if the voltage
of the battery reaches the cut-off voltage Vc. However, in the
present disclosure, a battery may be charged without any suspension
period after a voltage of the battery reaches the cut-off voltage
Vc, or a battery may also be charged with a shorter suspension
period than the embodiment of FIG. 2. Therefore, the present
disclosure is not limited to the embodiment depicted in FIG. 2.
[0049] Preferably, the phased decrement .DELTA.P of the charge
power is 1/5 or below the charge power CP0 applied when the early
charging mode terminates. In addition, the phased decrement
.DELTA.P of the charge power may be constant or may proportionally
increase or decrease.
[0050] Meanwhile, the battery charging apparatus 100 according to
the present disclosure may further include a memory unit 140 which
stores the cut-off voltage Vc, the phased decrement .DELTA.P of the
charge power, and the charge power condition (critical value) when
the late charging mode terminates.
[0051] The memory unit 140 may be a semiconductor element such as
RAM, ROM, EEPROM, which is well known in the art as a unit capable
of recording or erasing data, or a mass storage medium such as a
hard disk, but the present disclosure is not limited thereto.
[0052] The control unit 120 may be a microprocessor capable of
executing program codes for performing a dualized charging mode
according to the present disclosure. As an alternative, the control
unit 120 may be a semiconductor chip which implements control flows
of the dualized charging mode according to the present disclosure
as logic circuits. However, the present disclosure is not limited
thereto.
[0053] The battery charging apparatus according to the present
disclosure may be one component of a battery driving system which
includes a battery and a load supplied with power from the
battery.
[0054] The battery driving system may be, for example, an electric
vehicle (EV), a hybrid electric vehicle (HEV), an electric bike
(E-Bike), a power tool, an energy storage system, an
uninterruptable power supply (UPS), a portable computer, a cellular
phone, a portable audio device, a portable video device or the
like, and the load may be, for example, a motor for giving a
rotating force by the power supplied by the battery or a power
conversion circuit for converting the power supplied by the battery
into power required by various circuit parts.
[0055] Further, the battery charging apparatus according to the
present disclosure may be one component of a battery pack which
includes a cell assembly in which a plurality of battery cells is
connected in series or in parallel and a battery management system
(BMS) for controlling charging/discharging of the cell assembly. In
this case, the battery charging apparatus may be integrated with
the BMS or configure a separate circuit device.
[0056] Hereinafter, a method for charging a battery according to an
embodiment of the present disclosure will be described. Regarding
the method for charging a battery according to the present
disclosure, any component or operation already described in detail
in relation to the battery charging apparatus 100 will not be
described again.
[0057] The method for charging a battery according to the present
disclosure includes an early charging stage and a late charging
stage. The early charging stage is a stage in which a battery is
charged until a voltage of the battery rises to the preset cut-off
voltage Vc, and the late charging stage is a state in which the
battery is charged while lowering the charge power in phases. At
this time, a point of lowering the charge power in phases is
associated with a point at which the voltage of the battery reaches
the cut-off voltage Vc again by the lowered charge power.
[0058] The method for charging a battery according to the present
disclosure will be described with reference to FIGS. 1 and 4.
[0059] FIG. 4 is a schematic flowchart for illustrating a method
for charging a battery according to an embodiment of the present
disclosure. In FIG. 4, Steps S410 and S420 correspond to the early
charging stage, and Steps S430 to S460 correspond to the late
charging stage.
[0060] Referring to FIG. 4, first, in S410 of the early charging
stage, the control unit 120 controls the charging unit 130 so that
the battery is charged with a preset early charge power. The early
charging stage may use a constant-power manner, a constant-current
manner, a constant-voltage manner, or their mixtures.
[0061] Next, in Step S420, the control unit 120 determines whether
the voltage of the battery measured by the voltage measuring unit
110 rises to the preset cut-off voltage Vc. If the voltage of the
battery does not reach the cut-off voltage Vc, the process returns
to Step S410 and continues the charging process. Meanwhile, if the
voltage of the battery reaches the cut-off voltage Vc, the early
charging stage terminates and the process proceeds to Step S430 of
the late charging stage.
[0062] In S430 of the late charging stage, the control unit 120
lowers the charge power at the point when the early charging mode
terminates by a preset phased charge power decrement .DELTA.P. The
phased charge power decrement .DELTA.P may be constant or may
proportionally increase or decrease.
[0063] In addition, the process proceeds to Step S440 to determine
whether the charge power lowered in Step S430 reaches the critical
value. If the lowered charge power reaches the critical value, the
charging process terminates. Meanwhile, if the lowered charge power
does not reach the critical value, the process proceeds to Step
S450.
[0064] In Step S450, the control unit 120 outputs a control signal
corresponding to the lowered charge power, namely the late charging
stage, to the charging unit 130 and thus controls the charging unit
130 so that the battery is charged with a late charge power
CPn.
[0065] Next, in Step S460, the control unit 120 determines whether
the voltage of the battery measured by the voltage measuring unit
110 rises to the preset cut-off voltage Vc. If the voltage of the
battery does not reach the cut-off voltage Vc, the process returns
to Step S450 to continue the charging process. Meanwhile, if the
voltage of the battery reaches the cut-off voltage Vc, the process
returns to Step S430.
[0066] As above, the control unit 120 lowers the charge power in
phases and performs the late charging stage until the charge power
reaches the preset critical value, and finishes the charging
process if the charge power reaches the preset critical value. For
example, the critical value may be 0 W.
[0067] As described above, the cut-off voltage Vc is set higher
than the open circuit voltage when the battery is fully charged,
and preferably, the cut-off voltage Vc may be set so that the open
circuit voltage of the battery when the battery finishes charging
is 95% or above the open circuit voltage when the battery is fully
charged.
[0068] According to the present disclosure, in the late charging
stage, the phased charge power decrement .DELTA.P may be 1/5 or
below the charge power CP0 applied when the early charging stage
terminates. In addition, the phased charge power decrement .DELTA.P
may be constant or may proportionally increase or decrease.
[0069] The method for charging a battery according to the present
disclosure may further include a storing step for storing the
cut-off voltage Vc, the phased charge power decrement .DELTA.P, and
a charge power condition when the late charging stage terminates,
in the memory unit 140.
[0070] According to the present disclosure, a voltage level reached
at full charge of a battery may be raised in a simple and efficient
way. In addition, a voltage level reached at full charge of a
battery may be raised by setting a cut-off voltage Vc and a phased
charge power decrement .DELTA.P in consideration of characteristics
of a battery to be charged, service environments or the like.
Further, since a charging process is not performed based on a
measurement error which may occur during repeated charging
processes, a voltage level reached at full charge of a battery may
be raised regardless of the number of charging processes.
Experimental Example
[0071] Hereinafter, the present disclosure will be described in
more detail based on an experimental example. However, this
experimental example is just for illustration, and the present
disclosure is not limited thereto.
[0072] First, the battery charging apparatus according to the
present disclosure was connected to a fully-charged lithium
secondary battery having a capacity of 43.5 Ah, and then the
lithium secondary battery was placed in a chamber which was
maintained at a normal temperature. After that, while constantly
maintaining a charge power of 2.1 kW, the early charging mode was
performed until a voltage of the battery rose to 4.135V which
corresponds to the cut-off voltage Vc. Subsequently, while lowering
the charge power from 2.1 kW to 0.3 kW in phases, the late charging
mode was performed. At this time, the point of lowering the charge
power was associated with a point at which the voltage of the
battery rose to the cut-off voltage Vc by the lowered charge power.
In addition, the charge power was lowered seven times in total, and
the late charging mode terminated when the charge power became 0
W.
[0073] After the battery was completely charged according to the
experimental conditions, the open circuit voltage of the battery
was measured as 4.1253 V. Meanwhile, for the lithium secondary
battery used in this experiment, the lower limit of the charging
open circuit voltage corresponding to 100% of the SOC was 4.2 V.
However, in order to prevent overcharging, the fully-charging open
circuit voltage of the lithium secondary battery was set as 4.12 V
which corresponds to 95% of the SOC, while remaining a margin of
about 5%. However, after applying the battery charging method
according to the present disclosure, it was found that the open
circuit voltage of the battery had risen to 4.1253 V which
corresponds to 95.38%. From this experiment result, it may be
understood that if a battery is charged according to the present
disclosure, a level of an open circuit voltage reached at full
charge of a battery may be raised in a simple and efficient way,
thereby enhancing the capacity of the battery.
[0074] The present disclosure has been described in detail.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
disclosure, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
disclosure will become apparent to those skilled in the art from
this detailed description.
[0075] In addition, it should be understood that the components or
elements of the battery charging apparatus 100 of the present
disclosure shown in FIG. 1 or the like may not be physically but
rather logically distinguished therebetween.
[0076] In other words, it should be interpreted that since each
component or element of the battery pack according to the present
invention is a logic component or element, they fall within the
spirit or scope of the invention if they perform a function of a
logic feature of the present invention whether they operate
separately or integratedly, and even though they are named
otherwise, they fall within the spirit or scope of the invention if
they perform the same or similar function.
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